Multiple stage inflater

ABSTRACT

A MULTIPLE STAGE INFLATER INCLUDES A CYLINDRICAL PRESSURE VESSEL HAVING AN OPENING AT ONE END RECEIVING AN IGNITER ASSEMBLY ELECTRICALLY CONNECTED WITH AN INTERIAL SWITCH OR OTHER TYPE OF INDICATING MEANS PROVIDING A SIGNAL INDICATIVE OF DEFORMATION OR THE ONSET OF DEFORMATION OF A VEHICLE BODY. THE OTHER END OF THE VESSEL INCLUDES AN OUTLET SEALED BY A FLUID PRESSURE RUPTURABLE DIAPHRAGM. THE OUTLET COMMUNICATES BY A MANIFOLD AND DIFFUSER ASSEMBLY WITH A CONVENTIONAL INFLATABLE OCCUPANT RESTRAINT CUSHION. A PROPELLANT TUBE EXTENDS PARTIALLY THROUGH THE VESSEL FROM THE IGNITER ASSEMBLY AND IS FILLED WITH SUITABLE PYROTECHNIC MATERIAL, SUCH AS BLACK POWDER. THE TUBE INCLUDES A NUMBER OF CIRCULAR OPENINGS IN THE WALL THEREOF. A PRIMARY INFLATION TUBE SURROUNDS THE PROPELLANT TUBE AND DEFINES A FIRST CHAMBER COMMUNICATING WITH THE DIAPHRAGM. THE PRIMARY INFLATION TUBE IS PROVIDED WITH A NUMBER OF CIRCULAR OPENINGS AND A REED VALVE WHICH PERMITS FLOW FROM THE FIRST CHAMBER TO A SECOND CHAMBER DEFINED BY THE PRIMARY INFLATION TUBE AND THE INTERIOR WALL OF THE VESSEL. THE SECOND CHAMBER AND THE SPACE WITHIN THE FIRST CHAMBER BETWEEN THE PROPELLANT AND PRIMARY INFLATION TUBES IS FILLED WITH AIR AT A PRESSURE LESS THAN THAT REQUIRED TO RUPTURE THE DIAPHRAGM. UPON IGNITION OF THE PYROTECHNIC MATERIAL, THE RESULTANT FLUID OR GAS FLOWS FROM THE PROPELLANT TUBE TO THE FIRST CHAMBER TO RUPTURE THE DIAPHRAGM AND INITIATE INFLATION OF THE CUSHION. THE RESULTANT FLUID ALSO FLOWS OUTWARDLY THROUGH THE PRIMARY INFLATION TUBE OPENINGS AND REED VALVE TO THE SECOND CHAMBER TO MIX WITH THE AIR THEREIN AND PROVIDE INCREASED PRESSURE FLUID. THE INCREASED PRESSURE FLUID THEN FLOWS AT A LESSER RATE BACK THROUGH THE OPENINGS IN THE PRIMARY INFLATION TUBE AND TO THE CUSHION TO CONTINUE INFLATION THEREOF. THE REED VALVE PERMITS ONE-WAY FLOW ONLY SO THAT THE INCREASED PRESSURE FLUID FLOWS AT A LESSER RATE THAN THE RESULTANT FLUID TO THE CUSHION.   D R A W I N G

March 20, 1973 P, G. MCDQNALD MULTIPLE STAGE INFLATER Filed April 25, 1971 N VEN TOR.

ATTORNEY United States Patent O 3,721,456 MULTIPLE STAGE INFLATER Patrick G. McDonald, Pontiac, Mich., assigner to General Motors Corporation, Detroit, Mich. Filed Apr. 23, 1971, Ser. No. 136,869 Int. Cl. B601- 21/00 U.S. Cl. 280-150 AB 4 Claims ABSTRACT F THE DISCLOSURE A multiple stage inilater includes a cylindrical pressure vessel having an opening at one end receiving an igniter assembly electrically connected with an inertial switch or other type of indicating means providing a signal indicative of deformation or the onset of deformation of a vehicle body. The other end of the vessel includes an outlet sealed by a fluid pressure rupturable diaphragm. The outlet communicates by a manifold and diffuser assembly with a conventional inflatable occupant restraint cushion. A propellant tube extends partially through the vessel from the igniter assembly and is lilled with suitable pyrotechnic material, such as black powder. The tube includes a number of circular openings in the wall thereof. A primary inflation tube surrounds the propellant tube and defines a rst chamber communicating with the diaphragm. The primary inflation tube is provided with a number of circular openings and a reed valve which permits flow from the first chamber to a second chamber defined by the primary inflation tube and the interior wall of the vessel. The second chamber and the space within the first chamber between the propellant and primary inflation tubes is filled with air at a pressure less than that required to rupture the diaphragm. Upon ignition of the pyrotechnic material, the resultant uid or gas flows from the propellant tube to the lirst chamber to rupture the diaphragm and initiate inllation of the cushion. The resultant uid also tlows outwardly through the primary inllation tube openings and reed valve to the second chamber to mix with the air therein and provide increased pressure fluid. The increased pressure fluid then llows at a lesser rate back through the openings in the primary inllation tube and to the cushion to continue inflation thereof. The reed valve permits one-way llow only so that the increased pressure iluid llows at a lesser rate than the resultant lluid to the cushion.

This invention relates to a multiple stage inflater for inilating vehicle body occupant restraint cushions.

One of the features of this invention is that the multiple stage inllater includes pyrotechnic material providing a source of high pressure resultant fluid for rupturing a diaphragm to initiate inflation of an inllatable occupant restraint cushion and for augmenting a predetermined volume of low pressure fluid to increase the pressure thereof, with the increased pressure fluid continuing inllation of the cushion and llowing thereto at a controlled rate less than the rate of the resultant fluid to thereby provide multiple stage inflation. Another feature is that the llow of resultant iluid to the low pressure fluid is at a greater rate than the llow of the increased pressure fluid to the cushion. A further feature is that the pyrotechnic material is contained Within an elongated tube housed within an elongated primary inflation tube which communicates with a predetermined volume of low pressure fluid by two-way valve means and one-way valve means, the one-way valve means permitting only llow of the resultant lluid to the low pressure iluid to increase the pressure thereof and the two-way valve means permitting llow in both directions to thereby limit the rate of ilow of the increased pressure air to the cushion to ICC less than the rate of flow of the resultant tluid to the cushion.

These and other features of the inllater of this invention will be readily apparent from the following specilication and drawing wherein:

The single figure is a sectional view of an inllater according to this invention.

Referring now to the drawing, an inllater designated generally 10 according to this invention includes a generally cylindrical pressure vessel 12. One end of the vessel is closed by a wall 14 having an opening 16 therethrough. The opening 16 communicates with au internally threaded bore 18 which receives a threaded conventional igniter assembly 20. The igniter assembly is electrically connected with a source of power and a sensor which senses either vehicle deformation or the onset of vehicle deformation. Such a sensor is known to those skilled in the art and the details thereof are therefore not included. The other end of the pressure vessel 12 includes an internally threaded opening 22 which receives an externally threaded plug 24. The plug 24 includes a shouldered bore 26 which opens to a bore 28 of lesser diameter which in turn opens to a bore 30 of lesser diameter. The bores 26, 28 and 30` provide an outlet for the vessel. Bore 30 opens to a manifold 32 which is crimped at 33 to an extension of plug 24 and communicates in a known manner with an inflatable occupant restraint cushion by means of a dilfuser or otherwise. A conventional metal diaphragm 34 includes a dome portion extending across the opening of bore 28 and a llange portion seating against the shoulder between bores 26 and 28 and suitably secured thereto, such as by electron bearn welding. Diaphragm 34 is of the type which is ruptured upon the application thereagainst of pressure lluid in the order of 1200 p.s.i.

A propellant tube 36 has one open end suitably secured to the wall 14 of the vessel 12 around the opening 16. Tube 36 is filled with suitable pyrotechnic material such as black powder, which is ignitable by the igniter assembly 20 to provide a predetermined volume of resultant iluid at high pressure, such as in the order of 1600 p.s.i. The other end 38 of the tube 36 is closed by an integral or attached end wall and the tube is provided with a number of rows of axially spaced openings 40 in the wall thereof.

A primary inflation tube 42 surrounds the tube 36. A necked-down portion 43 at one end of the tube 42 is secured to the propellant tube 36 adjacent the open end thereof. The other end of the tube 42 is received within the bore 26 in engagement with a shoulder thereof to thereby properly locate both tubes 36 and 42 with respect to the axis of the vessel 10. The tube 42 includes a number of axially spaced openings 44 which are unaligned with the openings 40 in the tube 36. Tube 42 further includes one or more axially elongated slots 46, each of which is closed by a conventional reed valve 48, generally including a strip of spring metal overlying the slot and secured at one end, to the outer wall of the tube 42.

The tube 42 provides a first chamber within the vessel 10 and cooperates with the vessel in providing a second chamber designated generally 50. Chamber 50 is filled with air at a pressure of approximately 800 p.s.i. The rst chamber or space surrounding the propellant tube 36 is also at this pressure. Since the diaphragm 34 can only be ruptured by a much higher pressure lluid, such as 1200 p.s.i., the air within the first and second chambers has no effect on the diaphragm.

When the igniter assembly 20 ignites the pyrotechnic material within the tube 36, upon reception of a suitable signal, the pyrotechnic material creates a predetermined volume of high pressure resultant fluid, such as in the order of 2000 to 4000 p.s.i. This resultant fluid passes from the tube 36 outwardly through the openings 40v into the first chamber where it mixes with the air therein, ruptures the diaphragm 34, and initiates inflation of the cushion by flow through the bores 26, 28 and 30 and the manifold 32. The resultant uid also ows outwardly through the openings 44 and reed valves 43` and mixes with the air in the second chamber to provide increased pressure fluid therein. The reed valves 48` open under the ow of the resultant fluid to the second chamber so that the mixing of this uid with the air occurs very rapidly. Since the pressure in the rst chamber drops as the cushion is inated, a pressure differential is created between the first and second chambers. The increased pressure uid in the second chamber then starts to ow back through the openings 44 and into the rst chamber so as to pass through the bores 26, 28 and 30' to the manifold 32 to continue the infiation of the cushion through a second stage. Since the reed valves 48 are closed, the return fiow of the increased pressure fluid from the second chamber to the first chamber is at a lesser rate than the initial flow to the cushion so that the continued inflation of the cushion through the second stage requires a longer time period than the initial ination of the cushion. The openings 44 are calibrated to provide the desired rate of flow of the increased pressure uid from the second chamber to the first chamber. This rate of flow will, of course, be lower than that of the rate of primary resultant pressure uid to the cushion during the initial inflation thereof.

Thus, this invention provides an improved multiple stage infiater.

What is claimed is:

1. The combination comprising, a pressure |vessel having an outlet communicable with an inflatable occupant restraint cushion and sealed by a fluid pressure rupturable diaphragm, a first walled chamber provided in the vessel and communicating with the diaphragm, pyrotechnic means within the first chamber ignitable to provide a volume of resultant fluid at a pressure suicient to rupture the diaphragm, a second chamber in the vessel containing fluid at a pressure insuficient to rupture the diaphragm, first means including a series of openings in the wall of the first chamber providing two-way communication between the first and second chambers, pressure actuated valve means provided at certain of said openings, means igniting the pyrotechnic means to provide the 'volume of pressure fluid and rupture the diaphragm, the resultant uid fiowing at a predetermined rate through the outlet to initiate infiation of the cushion through a primary stage, the first means and valve means permitting ow of the resultant fluid to the second chamber to increase the pressure of the fluid therein, the increased pressure uid in the second chamber closing the valve means to restrict the number of openings permitting flow of the increased pressure uid from the second chamber to the first chamber and decrease the rate of ow from the second chamber to the first chamber to less than that from the first chamber to the second chamber and thereby continue ination of the cushion through a secondary stage of greater duration than the primary stage.

2. The combination comprising, a pressure Vessel having an outlet communicable with an inflatable occupant restraint cushion and sealed by a IHuid pressure rupturable diaphragm, a `lirst chamber provided in the vessel and communicating wtih the diaphragm, pyrotechnic means Within the first chamber ignitable to provide a volume of resultant uid at a pressure sufficient to rupture the diaphragm, a second chamber in the Ivessel separated from the first chamber by a common wall having a series of openings therein, the first and second chambers containing uid at a pressure insufiicient to rupture the diaphragm, differential fiuid pressure operated valve means controlling the ow of fiuid from the second chamber to the lfirst chamber, means igniting the pyrotechnic means to provide the volume of pressure tiuid and rupture the diaphragm, the resultant uid flowing at a predetermined rate through the outlet to initiate inflation of the cushion through a primary stage, the openings and valve means permitting fiow of the resultant uid to the second chamber to increase the pressure of the fluid therein, the increased pressure fluid in the second chamber closing the valve means to restrict the ow of the increased pressure liuid from the second chamber to the first chamber to a rate less than the rate from the first chamber to the second chamber and continue infiation of the cushion through a secondary stage of greater duration than the primary stage.

3. The combination comprising, a pressure vessel having an outlet communicable with an inflatable occupant restraint cushion and sealed by a fiuid pressure rupturable diaphragm, a first walled chamber provided in the vessel and communicating with the diaphragm, source means within the first chamber actuatable to provide a volume of iiuid at a pressure sufficient to rupture the diaphragm, a second chamber in the vessel containing fluid at a pressure insufficient to rupture the diaphragm, means including a series of openings in the rst chamber Wall communicating the first and second chambers, means actuating the source means to provide the volume of pressure uid and rupture the diaphragm to initiate infiation of the cushion, the communicating means permitting flow of the volume of pressure Afiuid at a predetermined rate to the second chamber to increase the pressure of the fiuid therein, and means operative upon an increase in the pressure of the fluid in the second chamber to block certain of the openings and restrict the flow of the increased pressure Ifluid from the second chamber to the first chamber to a rate less than the predetermined rate to continue inflation of the cushion.

4. The combination comprising, a pressure =vessel having an outlet communicable with an inatable occupant restraint cushion and sealed by a uid pressure rupturable diaphragm, a first chamber provided in the Vessel and communicating with the diaphragm, pyrotechnic means Within the -lirst chamber ignitable to provide a volume of resultant fluid at a pressure sufficient to rupture the diaphragm, a second chamber in the vessel containing uid at a pressure insufficient to rupture the diaphragm, first -means providing two-way communication between the iirst and second chambers, second means providing one-way communication from the Afirst chamber to the second chamber, means igniting the pyrotechnic means to provide the volume of pressure fiuid and rupture the diaphragm, the resultant fluid flowing at a predetermined rate through the outlet to initiate ination of the cushion through a primary stage, the first and second means permitting flow of the resultant fiuid to the second chamber to increase the pressure of the fluid therein, the first means restricting flow of the increased pressure fluid from the second chamber to the first chamber to a rate less than the rate from the 'first chamber to the second chamber to continue iniation of the cushion through a secondary stage of greater duration than the primary stage.

References Cited UNITED STATES PATENTS 3,163,014 12/1964 Wismar 23-281 X 2,390,749 12/1'945 'Swift 137-599 X 3,527,472 `9/:1970 Chute et al. 280150 AB 2,214,656 8/19'40 Hubbard 137 599' 3,117,424 1/19164 Hebenstreit 222-3 X KENNETH H. BETTS, Primary Examiner U.S. C1. X.R. 102-39; 137-599 

